The serial control system that a kind of separate wavelengths is selected fast
Technical field
The invention belongs to the spectral instrument technical field, specifically, the present invention relates to the serial control system that a kind of separate wavelengths is selected fast.
Background technology
Difference Absorption and wavelength are important method in the spectroscopy measurements to measuring method.For carrying out the measurement of atmospheric ozone total amount distribution on global, the U.S. utilizes wavelength that measuring technique is developed total amount of ozone drawing spectrometer (TOMS) since the end of the seventies in last century.For realizing each is surveyed the quick measurement of wavelength, this instrument adopts fixed grating, array exit slit spectrometer and wavelength selective pan, by single photodetector the signal of 6 separate wavelengths is measured chronologically.Here, realization measuring-signal and detection wavelength accurately is the complete machine key of success synchronously.Existing way is that (document 1:N81-22393 sees reference, Multi-Channel Chopper System for Total Ozone Mapping Spectrometer) provides reference frequency by clock, make brushless motor speed stable by phase lock circuitry, wavelength selective pan and clock synchronization and with the locking of stationary phase and exit slit realize surveying the synchronous of wavelength and exit slit.The subject matter of this control system is stability and the phase-locked accuracy requirement height that the wavelength selective pan is rotated, and promptly accurately locks to this Mechatronic Systems requirement precise synchronization of clock, phase lock circuitry, brushless electric machine and wavelength selective pan and with stationary phase and exit slit.When the phase place of wavelength selective pan and exit slit changes or wavelength selective pan rotary speed unstabilization regularly, all will cause measuring-signal and to survey wavelength asynchronous, this will cause detectable signal the measurement mistake, lose even cause the inefficacy of complete machine.Operation result according to nimbus-7 satellite total amount of ozone drawing spectrometer shows, the reduction of the phase-locked precision of wavelength selective pan, make measuring-signal with survey wavelength asynchronous be this instrument data lose and the major reason of final complete failure (document 2:NASA RP-1384 sees reference, Nimbus-7 Toatal Ozone Mapping Spectrometer (TOMS) Data Products User ' s Guide, 1996, Section 4.7).
Summary of the invention
Therefore, the objective of the invention is to overcome prior art and carrying out separate wavelengths when measuring fast, measuring-signal easily produces nonsynchronous problem with surveying wavelength, the serial control system of wavelength selective pan-sampling pulse-AD collection of proposes a kind ofly not to be subjected to that wavelength selective pan rotational stability influences, measuring-signal and detection wavelength are synchronous, reliable and stable for a long time.
For achieving the above object, the quick serial control system of selecting of separate wavelengths provided by the invention comprises driving circuit, dc brushless motor, wavelength selective pan, position transducer, photodetector and signal processing unit; Described driving circuit is used to drive dc brushless motor, and described dc brushless motor is used to drive described wavelength selective pan and rotates; The exit slit array of spectrometer and described photodetector lay respectively at the both sides of described wavelength selective pan; Described wavelength selective pan has wavelength selecting hole and sampling pulse tooth, described wavelength selecting hole is the through hole with certain subtended angle and width, the subtended angle of each wavelength selecting hole does not overlap each other, and each wavelength selecting hole position corresponding to the exit slit of different wave length in the exit slit array of the distance of the rotating shaft of described wavelength selective pan and spectrometer is corresponding; Described sampling pulse tooth is positioned at the edge of described wavelength selective pan, and described sampling pulse tooth is corresponding one by one with each wavelength selecting hole; Described position transducer is used to detect described sampling pulse tooth near the edge of described wavelength selective pan; Described position transducer and photodetector are transferred to described signal processing unit with signal.
In the technique scheme, described wavelength selective pan is installed in the rotating shaft of dc brushless motor, and the axis of wavelength selective pan overlaps with the rotating shaft of dc brushless motor, and after being placed on the spectrometer exit slit, near the exit slit place.
In the technique scheme, described wavelength selecting hole is curved.
In the technique scheme, the width of described wavelength selecting hole is wide greater than the seam of the exit slit of described spectrometer.
In the technique scheme, the beginning of described sampling pulse tooth, described wavelength selecting hole located and being centered close on the same straight line of described wavelength selective pan.
In the technique scheme, described sampling pulse tooth is the breach that is positioned at described wavelength selective pan edge.
In the technique scheme, described wavelength selective pan is divided into the free area and wavelength is selected the district; Described free area and wavelength select the district respectively to occupy certain subtended angle, and described wavelength selecting hole all is positioned at the subtended angle that described wavelength is selected the district.
The present invention has following technique effect: measure the spectrometer of a plurality of separate wavelengths to adopting single photodetector, the serial control system that utilizes this wavelength selective pan-sampling pulse-AD to gather makes measuring-signal and surveys wavelength reliable synchronization steady in a long-term.By being loaded with the design of wavelength selecting hole and sampling pulse tooth on the wavelength selective pan simultaneously, it is synchronous fully that sampling pulse tooth and wavelength selecting hole are had by designing requirement, eliminated wavelength selective pan speed stability effectively to measuring-signal and the synchronous influence of detection wavelength.Even work as environmental baseline or dc brushless motor, drive circuitry parameter variation, can not cause losing of data when making direct current brushless motor speed change yet, thereby improve the rate of obtaining of data and the reliability of complete machine with instability.Because native system is surveyed the replacing of wavelength and finished by the rotation of wavelength selective pan, thereby realized surveying the quick selection of wavelength.
Description of drawings
Below, describe embodiments of the invention in conjunction with the accompanying drawings in detail, wherein:
Fig. 1 is the principle schematic that wavelength of the present invention is selected serial control system;
Fig. 2 is a wavelength selective pan synoptic diagram of the present invention;
Fig. 3 is a signals collecting subprogram process flow diagram of the present invention.
1----driving circuit 2----dc brushless motor 3----wavelength selective pan
4----position transducer 5----photodetector 6----signal processing unit
7----spectrometer exit slit
The 2-1------wavelength is selected 2-2------free area, district
2-1-1------wavelength selecting hole 2-1-2------sampling pulse tooth
Embodiment
Embodiment
As shown in Figure 1.Present embodiment comprises driving circuit 1, dc brushless motor 2, wavelength selective pan 3, position transducer 4, photodetector 5 and signal processing unit 6 compositions.
Driving circuit 1 becomes driving dc brushless motor 2 needed three-phase supply with dc power supply, press dc brushless motor 2 required sequential and supply with dc brushless motor 2, rotate to drive dc brushless motor 2, dc brushless motor 2 is used to drive the rotation of wavelength selective pan 3.Dc brushless motor 2 adopts brushless dc torque motor, and rotating speed is 250rpm.
Wavelength selective pan 3 is installed in rotating shaft one end of dc brushless motor 2, and the axis of wavelength selective pan 3 overlaps with the rotating shaft of dc brushless motor 2.After wavelength selective pan 3 is placed on spectrometer exit slit 7, near the exit slit place.The structure of wavelength selective pan 3 as shown in Figure 2.It is divided into two districts, and one is that wavelength is selected district 2-1, accounts for 288 °, is 80% of wavelength selective pan; 20% of remainder is to not busy district 2-2.
Wavelength is selected to be placed with wavelength selecting hole 2-1-1 and sampling pulse tooth 2-1-2 in the district 2-1.In this example is under the situation of six detection wavelength, and six wavelength selecting hole 2-1-1 and six sampling pulse tooth 2-1-2 are arranged respectively.Each wavelength selecting hole 2-1-1 center equals the distance of spectrometer exit slit array center to wavelength selective pan 3 axis to the radial distance of wavelength selective pan 3 rotating shafts, and is corresponding to guarantee each wavelength selecting hole position corresponding to the exit slit of different wave length in the exit slit array of the distance of the rotating shaft of described wavelength selective pan and spectrometer.Each wavelength selecting hole 2-1-1 respectively accounts for certain subtended angle in wavelength is selected district 2-1 scope, each other non-overlapping copies; Under this routine situation, the maximum subtended angle of wavelength selecting hole 2-1-1 should be less than 48 °.The width of wavelength selecting hole 2-1-1 is chosen and should be made its width greater than the single exit slit of spectrometer, but does not make the optical radiation of facing two exit slits mutually simultaneously by same wavelength selecting hole 2-1-1 according to the situation of surveying wavelength again.Wavelength selecting hole 2-1-1 is used to survey choosing of wavelength, and promptly along with the rotation of wavelength selective pan 3, in particular moment, the optical radiation that a wavelength is only arranged is by wavelength selecting hole 2-1-1, and the optical radiation of its commplementary wave length is all stopped by wavelength selective pan 3.
Sampling pulse tooth 2-1-2 be positioned at wavelength selective pan 3 edge, each wavelength selecting hole 2-1-1 begin the place; The subtended angle of sampling pulse tooth 2-1-2 relative wavelength selective pan 3 rotating shafts is determined according to the rotating speed of wavelength selective pan 3 and the response characteristic of position transducer 4, so that position transducer 4 has enough responses, be convenient to determine the reference position of sampling pulse tooth 2-1-2, be taken as 2 ° in this example; Tooth depth is taken as 4mm in this example so that position transducer is measured as suitablely.Sampling pulse tooth 2-1-2 is used to provide the reference position of wavelength selecting hole.
The free area 2-2 of wavelength selective pan 3 is used for the location of wavelength selective pan 3 starting points and Signal Pretreatment, packing.
Photodetector 5 adopts the R7111-01 photomultiplier.After photodetector 5 is placed on wavelength selective pan 3, be close to the wavelength selective pan, and be in the centre position of spectrometer exit slit array; The height of photodetector 5 is highly consistent with spectrometer exit slit 7, makes photodetector can receive optical radiation by each exit slit of spectrometer.Photodetector 5 will be converted to electric signal by the optical radiation of spectrometer exit slit 7 and supply with signal processing unit 6.
By the rotation of wavelength selective pan 3, wavelength selecting hole 2-1-1 chooses the optical radiation (be 6 in this example and survey wavelength) of respectively surveying wavelength successively by designing requirement.When the optical radiation of given detection wavelength arrives photodetector 5 by wavelength selecting hole 2-1-1, with the corresponding sampling pulse tooth of wavelength selecting hole 2-1-1 2-1-2 also in-position sensor 4.Position transducer 4 adopts U.S.'s HOA1875 type optical chopper of Newire Inc. suddenly.Position transducer 4 is placed on spectrometer exit slit 7 one sides, and its height is highly identical with spectrometer exit slit 7.When wavelength selective pan 3 rotates, sampling pulse tooth 2-1-2 on the wavelength selective pan 3 will be by position transducer 4, the light beam of cutting position sensor 4, when making sensor 4 positions, sampling pulse tooth 2-1-2 in-position, position transducer 4 outputs one high level pulse, be sampling pulse, supply with signal processing unit 6.
Signal processing unit 6 is made up of signal amplifier, AD Acquisition Circuit, single-chip microcomputer and corresponding software.Its effect is that the signal that photodetector 5 and position transducer 4 measured is amplified, the measuring-signal of photodetector 5 is carried out AD gathers, and the wavelength of being surveyed according to design identification.
After signal processing unit is received sampling pulse, begin to carry out data acquisition by the software control signal processing unit, obtain the detectable signal value of this wavelength; And according to designing the wavelength that identification is surveyed.
Sampling pulse and detectable signal capture program job step are as follows: referring to Fig. 3.
Step S3-1 is according to the starting point of the judgement of the free area 2-2 on the wavelength selective pan 3 wavelength selective pan 3;
Step S3-2 according to the sampling pulse that position transducer 4 provides, determines sampling pulse tooth 2-1-2, is the position of wavelength selecting hole 2-1-1, begins to carry out data acquisition.When position transducer collected sampling pulse, signal processing unit at first carried out the premeasuring that AD gathers, and carried out the judgement of photodetector amplifier gain shelves according to the prediction value, and carried out the setting of photodetector amplifier gain shelves;
Step S3-3 after setting photodetector amplifier gain shelves, carries out AD to detectable signal and gathers.For reducing the AD transformed error, AD gathers and carries out continuously 16 times, and measured value is the mean value of 16 AD collections;
Step S3-4 after detection data AD collection is finished, judges whether the epicycle spectral measurement is finished.Signal at 6 detecting bands that require to measure is not finished, and promptly the sampling pulse counting was less than 6 o'clock, and the epicycle spectral measurement is not finished; Should return step S3-2 this moment, continues to search the next sampling pulse tooth 2-1-2 on the wavelength selective pan 3.When sampling pulse counting equaled 6, the epicycle spectral measurement was finished, then with the detection data packing with carry out exporting after the necessary pre-service, waited for the next round spectral measurement.